General Transcription Factor IIB (GTF2B)

Transcription factor II B (TF_IIB) is one of several general transcription factors that make up the RNA polymerase II preinitiation complex. It is encoded by the TFIIB gene.Transcription factor IIB localizes to the nucleus where it forms a complex (the DAB complex) with transcription factors IID and IIA.

The protein serves as a bridge between IID, the factor which initially recognizes the promoter sequence, and RNA polymerase II. It is involved in the selection of the transcription start site: mutations in TFIIB cause a shift in the transcription start site. TFIIB is conserved between eukaryotes and archaebacteria. One serum, which strongly inhibited transcription in a cell-free system, was shown to contain antibodies directed against human TFIIB.